Books historically have been stored on shelves in libraries. However, over the past few decades libraries have become more than just a place to check out a book. Rather, they have become places where people come to work, study, etc. Consequently, the need has arisen for more work spaces in libraries. As a result, libraries have begun storing some books in offsite storage facilities to reclaim space within the library for other purposes.
Existing offsite storage facilities typically consist of a warehouse filled with book shelves or racks. Harvard University was the first to introduce high density storage facilities in the mid-1980s, where books are sorted by size (as opposed to LC call numbers or Dewey Decimal) and stored in cardboard boxes or trays provided on the racks. See FIGS. 1-3. Adjacent racks are separated by an aisle. Computer software is used to inventory the books and assign a location within the warehouse for a book. The warehouse is climate controlled, whereby the temperature and humidity levels are strictly managed. For example, a book depository will typically maintain between 55° F.+/−5° F. and 35%+/−5% relative humidity. When a book is ordered, a worker ascertains the location of the book from the computer and operates a forklift in the aisle between adjacent racks to manually retrieve the book. See FIGS. 2A-2C.